Lid for a mug or tumbler



FIG. 1 is a top side perspective view of a lid for a mug or tumbler showing our new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a right side elevational view thereof;

FIG. 4 is a left side elevational view thereof; and,

FIG. 5 is a top plan view thereof.

The broken lines in the drawings are for illustrative purposes only and form no part of the claimed design. 

The ornamental design of a lid for a mug or tumbler, as shown and described. 